Cutting tools with round face tooth inserts

ABSTRACT

Saws have teeth inserts which present on each tooth a circular cutting edge resulting from truncating spheres of hard or hardenable material to form round surfaces facing the direction of sawing motion and presenting round cutting edges at the teeth tips having a positive or negative rake as desired.

United States Patent 1191 Tyler Jan. 29, 1974 CUTTING TOOLS WITH ROUNDFACE [56] References Cited TOOTH INSERTS UNITED STATES PATENTS Inventor:Robert y Westminister, 3,537,491 11/1970 Kolesh 144/218 x Mass.3,104,562 9/l963 Kolesh 76/1 I2 [73] Assignee: Wallace-MurrayCorporation,

pitchburgh, Mass Primary Examiner-Donald R. Schran [22] Filed: Sept. 7,1972 21 A I N 286 956 [57] ABSTRACT I 1 pp Saws have teeth inserts whichpresent on each tooth a circular cutting edge resulting from truncatingspheres Cl 83/835, 1 of hard or hardenable material to form roundsurfaces 1414/2153 facing the direction of sawing motion and presenting[Sl Int. Cl. round cutting edges at the teeth tips having a, positive[58] Field of Search 144/218; 76/1 12; 29/95; or ti k s d sired.

5 Claims, 6 Drawing Figures PAIENIEDJINZQIQM FIG I FIG 2 FIG 5 CUTTINGTOOLS WITH ROUND FACE TOOTH INSERTS This invention relates tocarbide-tipped saws and more particularly to carbide-tipped saws havingcarbide tips of novel configuration rendering the saws less expensive tomanufacture and easier to maintain and to a method of making such saws.1

BACKGROUND OF THE INVENTION The welding of spherically-shaped inserts ofa hard metal into the tooth tip portions of a saw has been described inUS. Pat. No. 3,104,562. Such'sphericallyshaped inserts have certainadvantages over rectangular inserts as described in said patent.Nevertheless, in finishing such tips, the several faces including theleading face, the two side faces and the trailing face were all groundand in separate operations In US. Pat. No. 3,537,491 carbide balls werealso used, being ground to present cutting edges which were eithercurved in a plane of revolution of a circular saw (FIG. 3) or in a planeperpendicular thereto (FIGS. 6 and 7) or only slightly tilted out of oneof said planes (FIGS. 10-13) i.e., at a backward angle of more than 180to the direction of saw motion.

SUMMARY OF THE INVENTION In accordance with this invention, whilespherical inserts are still used, each finished tooth is produced byonly a single grinding operation which truncates the sphere in suchmanner that the finished tooth presents a round nose facing thedirection of sawing movement of the blade and has a cutting edge havinga rake anywhere from 30 positive to 30 negative. By the use of suchconstruction, balls of varying diameters may be used depending upon howlarge a kerf is desired and the inserts may be ground to any distancebeyond the centers giving more and more top, back and side clearancesautomatically as the grinding proceeds.

Typical embodiments of the invention are shown in the accompanyingdrawings wherein:

FIG. 1 is a perspective view of a carbide-tipped saw of the inventionwith the direction of sawing movement being upwardly as indicated by thearrow;

FIG. 2 is an exploded view of a portion of a saw tooth having aspherical cavity into which a sphere of carbide is inserted;

FIG. 3 is a side elevational view of the detailed secative rake ascontrasted with the positive rake of the tip of FIG. 3.

DESCRIPTIONS OF SP'ECIFIC'EMBODIMENTS OF THE INVENTION FIG. 1 shows aportion 'of a band saw having steel teeth 20 and inserted ground carbidetips 22.

The tips are formed from spheres one of which is shown as 24 in FIG. 2which are seated in spherical cavities 26 which are self-formed in theleading edges of the different teeth if the balls are affixed bywelding; or in some instances the spherical cavities may be preformedbefore inserting and affixing the balls by welding means. After thespheres are fixed in the cavities, the spheres are truncated to give apositive or negative rake. Thus in FIG. 3 the rake is 10 positive, thedirection of sawing motion being indicated by the arrow, but it could beanywhere from 0 to 30 positive. The diameter of the flat truncatingsurface is left greater than the thickness of the saw blade teeth 30 soas to make circular edge 27 have kerf-cutting portions extendingoutwardly on both sides and beyond the body of the saw as indicated inFIG. 5.

In FIG. 6 the tooth 30a is of different contour so as to seat a ball 24bwhich is truncated so that its circular truncating surface 28a providesa tip having a rake of 20 negative, the direction of sawing motion againbeing indicated by the arrow. But the rake could be anywhere from O30negative.

The sphere inserts may be of any hard material which will function toincrease the cutting life of the saw as a whole and may be applied, ifdesired, to the teeth of circular saws, band saws, hack saws, Sabresaws, milling cutters and other cutting tools.

What is claimed is:

l. A saw blade having teeth spaced along an edge thereof a truncatedsphere affixed to the leading edge of each tooth, the truncating surfaceof said sphere extending all the way across the leading edge of eachtooth and forming a succession of circular edges lying in planesdisposed at angles to the direction of cutting motion of said blade andforming a circular cutting edge at the tip of each tooth.

2. A saw blade as claimed in claim 1 wherein the diameters of saidcircular edges are uniform and exceed the thickness of said teeth topresent curved kerfforming cutting edges on the sides of the teeth.

3. A saw blade as claimed in claim '1 wherein the angles are the sameand provide a 030 positive rake for the teeth.

4. A saw blade as claimed in claim 1 wherein the angles are the same andprovide a 0-30 negative rake for the teeth.

5. The method of making a saw blade with circular cutting edges on eachtooth comprising affixing a ball to the leading edge of each tooth andthen grinding the ball beyond its center to-create a circular cuttingedge lying in a plane providing a tooth tip having a rake between 30positive and 30 negative.

1. A saw blade having teeth spaced along an edge thereof a truncatedsphere affixed to the leading edge of each tooth, the truncating surfaceof said sphere extending all the way across the leading edge of eachtooth and forming a succession of circular edges lying in planesdisposed at angles to the direction of cutting motion of said blade andforming a circular cutting edge at the tip of each tooth.
 2. A saw bladeas claimed in claim 1 wherein the diameters of said circular edges areuniform and exceed the thickness of said teeth to present curvedkerf-forming cutting edges on the sides of the teeth.
 3. A saw blade asclaimed in claim 1 wherein the angles are the same and provide a 0*-30*positive rake for the teeth.
 4. A saw blade as claimed in claim 1wherein the angles are the same and provide a 0*-30* negative rake forthe teeth.
 5. The method of making a saw blade with circular cuttingedges on each tooth comprising affixing a ball to the leading edge ofeach tooth and then grinding the ball beyond its center to create acircular cutting edge lying in a plane providing a tooth tip having arake between 30* positive and 30* negative.